The Inaugural Prize-2014

The inaugural Prize was awarded to Mr Jan Jeske. It was presented by Marie Snook at the RMIT Award Evening on 27th March, 2014.

Jan is a German international student who moved to RMIT to do a theory/computation PhD in condensed matter physics. Jan did his undergrad at Karlsruher Institute of Technology.

 The following are Jan's comments on being awarded the Prize:

I am deeply honoured to be the first recipient of the Ian Snook Physics Prize, which honours Ian Snook, a great man, who shaped the physics department at RMIT. When I arrived at RMIT to start my PhD Ian regularly walked past my desk on the way to his office and stopped for a chat, be it about physics or about his travels to France and Germany. As time went by I learned that this friendly professor was not only someone who everyone in my office liked to chat with but that he was also a highly respected and well liked mentor to almost everyone in the department. I’m glad to have met him and am honoured to receive this prize in his name.

This prize allowed Jan to attend the conference “The Principles and Applications of Control in Quantum Systems (PRACQSYS 2014)” hosted by the Isaac Newton Institute for Mathematical Sciences in Cambridge, United Kingdom in August 2014.

Jan very much appreciated the opportunity to present his research overseas. 

In his words:

"I am very grateful and hope that the Ian Snook Prize will continue to support PhD students in their travel to conferences and collaborators."

Jan submitted his PhD shortly after receiving the prize and continues to work at RMIT as a postdoc for A.Prof. Andrew Greentree.

 

Marie Snook's Speech: The 2014 Ian Snook Prize Presentation.

It is with great pleasure and pride that I present the inaugural “Ian Snook Physics Prize”.

There are many people to thank.

  1. Ms Susie Bass and Professor Salvy Russo, who were instrumental in establishing the Award.
  2. Professor Margaret Gardiner and Professor Peter Coloe, who enabled the Award to be a significant one through RMIT’s generous contribution.
  3. Applied Physics, who held a fantastic fund raising Trivia Night and
  4. The Applied Sciences School which has provided funds for this inaugural prize.

There have also been many donations (and these are on-going) from colleagues, friends and family. This is a wonderful tribute to Ian.

A big thanks to everyone.

Ian dedicated 40 years of service to RMIT Physics.

He had an outstanding international research career, but his greatest pride came from the achievements of his students and colleagues. He was able to inspire and guide, offering friendship and advice, encouragement and support to ensure success of each individual.

Ian has left a great legacy through his former students, and this award will ensure that this legacy continues.

As a PhD student, Ian was inspired by a pioneer in his field, the late Dr John Barker, who Ian met when he attended his first international Conference. A few years later he was able to spend a year working with John in the US. This experience shaped Ian’s  career.   

It is hoped that the recipients of this prize will be able to benefit in a similar way.

Jan Jeske is a very worthy recipient of the Ian Snook Physics Prize, and we wish him every success. It is fitting that he comes from Germany, where Ian established a valuable collaboration over many years.

Congratulations Jan and good luck.

 

Jan's Research:

Open Quantum Systems

What is the research field of ‘open quantum systems’? ‘Quantum’ refers to small scale physics (on the scale of single atoms) and ‘open’ refers to the fact that in experiments on such a small scale the systems are often not perfectly isolated (closed systems) but instead experience perturbations from their environment such as fluctuating magnetic or electric fields. These perturbations are usually unwanted but hard to eliminate and therefore referred to as ‘quantum noise’.

Why study quantum systems?

The theory of quantum mechanics has fascinated and surprised physicist for about a hundred years now. However, only in the last few decades have we started to be able to control and measure a variety of different quantum systems which bears the promise of future technology based on quantum systems. Particularly the idea of a quantum computer, which would be able to perform certain types of calculations exponentially faster than our current ‘classical’ computers is driving research efforts around the globe. But also other fields profit from a deeper understanding of quantum systems, e.g. quantum metrology, the field that pushes the boundaries of the most precise measurements to set new standards for time, electric current and other variables or quantum biology, a rather new field or research, which arose from the discovery, that in the photosynthetic complexes of plants quantum mechanical processes seem to play a role.

Examples of controllable quantum systems

There are a variety of experiments which control quantum systems. One group is actual single atoms or ions, for example ions which are captured in an ion trap and held in position with electric fields, or point defects in a crystal lattice, such as the nitrogen-vacancy centre in a diamond lattice. These types of systems are usually controlled with lasers, which are tuned to the particular energy scale of the system. Different lasers allow to manipulate and measure the atoms. Another group of experiments involves ‘artificial atoms’ which consist of electric circuits of superconducting materials. These experiments, which need to be performed at very low temperatures to guarantee superconductivity, i.e. no electric resistance, also show quantum mechanical behaviour with quantum states that behave like single atoms. These systems are controlled and measured via electromagnetic pulses in the circuit.

Coherent versus decoherent behaviour

Both groups of experiments are not fully isolated and coherent but are exposed to noise from their respective environment which introduces random changes in their behaviour, so-called decoherence. The environmental perturbations add up over time to a point where the system is in a purely random state. The time during which a quantum system can be used without too much disturbance is called the coherence time. After the coherence time the system needs to be initialised in a certain state again to be useful. The coherence times vary between systems but are usually of the order of milliseconds or even microseconds. Although this seems extremely short it is enough to perform many experiments however decoherence is still one of the major hindrances on the way to quantum technology. This highlights the importance to understand quantum noise and decoherence better.

If you are a student and interested in this field contact Jared Cole, Andrew Greentree or Jan Jeske.  

My research at RMIT University

Together with my senior supervisor, Dr. Jared Cole, I studied the influence of spatial correlations in the environmental noise of quantum systems. Spatially correlated noise means that different spatial points of a quantum system are exposed to noise that comes from the same source.

We first needed to extend an existing formalism, the Bloch-Redfield equations, to be able to model spatially correlated noise efficiently and comprehensively and described the different effects of spatially correlated and uncorrelated noise in a very general way. This work was published in [1]. We merged our approach with the work of Nicolas Vogt from the Karlsruhe Institute of Technology in Germany who had been working on an implementation of Bloch-Redfield equations which takes much less computational power, published in [2].

We then applied this formalism to transport processes in spin chains and networks. This is an important application for short range transport of quantum information. Spatial noise correlations reduce the detrimental effects of noise considerably for the quantum states involved in transport processes. The results are published [3].

In collaboration with Susana Huelga from the Universität Ulm, Germany, we found that correlated decoherence is highly relevant to quantum metrology, a research field that tries to increase the precision of frequency measurements for given resources. In the standard quantum limit the precision increases with sqrt(n), where n is the number of ions used in the measurement. Using entangled states this scaling can be improved to be directly proportional to n, which for large numbers of ions means an enormous increase in precision. Uncorrelated noise in experiments however has been found to destroy this advantage entirely. We found that for correlated decoherence this advantage can be restored. On top of that previous experimental measurements of coherence times in trapped ion experiments showed characteristics, which can only be explained with strongly correlated noise. A preprint of the results can be found in [4].

Another interesting application of our formalism is in the field of quantum biology. Recently it has been found that at least certain photosynthetic organisms, which harvest and convert light, seem to involve quantum coherent processes. Although these light-harvesting complexes are quite different systems compared to the usual controlled quantum experiments we pointed out the similarities and showed that the formalism is a helpful tool to explore these biological systems as well.

 

 

[1] Jan Jeske, Jared H Cole, Derivation of Markovian master equations for spatially correlated decoherence. Phys. Rev. A 87, 052138 (2013)

[2] Nicolas Vogt, Jan Jeske, Jared H. Cole, Stochastic Bloch-Redfield theory: Quantum jumps in a solid-state environment. Phys. Rev. B 88, 174514 (2013)

[3] Jan Jeske, Nicolas Vogt, Jared H. Cole, Excitation- and state-transfer through spin chains in the presence of spatially correlated noise. Phys. Rev. A 88, 062333 (2013)

[4] Jan Jeske, Jared H. Cole, Susana Huelga, Quantum metrology in the presence of spatially correlated noise: Restoring Heisenberg scaling. arXiv:1307.6301